Your question is incomplete. What matrix stack does your glLoadIdentity apply to: glMatrixMode(GL_MODELVIEW) or glMatrixMode(GL.GL_PROJECTION)? You should be working on the GL_MODELVIEW stack.

Since your glVertex2f 2nd argument is always 200, Your code is drawing a line centered at approximately (228,200). Is that what you meant to do?

Second, when you apply rotations/translations/scale/etc it is convenient to think of the order of operations in global coordinates in reverse order as the code. By this I mean in your case reading the code from glBegin _UP_. Your code directly means that you first apply a rotation then apply a translation second. You are applying a rotation of 45 degrees about the origin (0,0) with the line centered at (228,200) -- this is why your radius appears to be so large.

I suggest taking the time to read the Redbook Chapter 3 (http://glprogramming.com/red/chapter03.html).

Here is a quick code to show how to rotate around a particular vertex point (x=215, y=200). Note the beginning fast roation for ~1 second is due to a timer calibrating to a fixed FPS

glPushMatrix();
glTranslatef(x,y,0); // 3rd move rotated line back to original location
glRotatef(gAngle,0.,0.,1.); // second rotate line about origin
glTranslatef(-x,-y,0); // first translate line to origin